Proliferation of refrigerants for refrigeration systems, such as air conditioning and heat pump systems, increases the likelihood that the refrigerant in a particular system may be different than expected. Mixing of refrigerant types, and consequent refrigerant contamination, must be avoided. Steps have been taken in some industries, such as the motor vehicle industry, to prevent mixing and contamination of refrigerants by requiring different service fittings, and separate recycling and service equipment, for different refrigerant types. U.S. Pat. Nos. 5,158,747 and 5,295,360, both assigned to the assignee hereof, disclose instruments for identifying refrigerant type prior to initiating service on the refrigeration equipment, and thereby helping to avoid mixing and contamination of refrigerants.
A problem that must be addressed, however, lies in the handling of flammable refrigerants, such as hydrocarbon refrigerants, and refrigerants that may have become flammable through mixing and contamination. It is conventional practice in systems for recovering refrigerants from equipment under service, and in other refrigerant handling systems, to employ an electrically operated refrigerant compressor and one or more electrically operated solenoid valves for controlling flow of refrigerant through the compressor. U.S. Pat. Nos. 4,261,178, 4,768,347, 5,211,024 and 5,261,249, all assigned to the assignee hereof, illustrate technology of this character. It is a general object of the present invention to provide a system and method for handling flammable refrigerants such as hydrocarbons, or contaminated refrigerants that may be flammable, that does not employ or require electrical power at the refrigerant compressor or at any of the components in the refrigerant flow path.